Polyol composition for producing flexible polyurethane foam and flexible polyurethane foam

ABSTRACT

A polyrotaxane is blended into a polyol composition, which can reduce the tensile stress of a flexible polyurethane foam. A vertical compressive stress due to the weight of a sitting user and a tensile stress due to the input of lateral vibrations act on a urethane pad. However, by reducing the tensile stress of the flexible polyurethane foam, the direction (inclination) of a resultant force obtained by combining the compressive stress and the tensile stress can be brought close to the vertical direction. Thus, the angle of inclination of the user&#39;s hip (ischium) on the urethane pad to the vertical direction due to the input of lateral vibrations can be reduced, so that the sense of wobble of the urethane pad can be reduced.

TECHNICAL FIELD

The present invention relates to polyol compositions for producingflexible polyurethane foams and flexible polyurethane foams andparticularly relates to a polyol composition and a flexible polyurethanefoam from which a urethane pad capable of reducing a sense of wobble canbe produced.

BACKGROUND ART

Urethane pads used for seats mounted on conveyances, such as vehicles,boats, ships, and aircraft, furniture chairs, and the like may giveusers a sense of lateral wobble. For example, an urethane pad mounted ona vehicle may be deformed by vibrations in a low-frequency band (forexample, about 1 Hz) input when the vehicle goes around a mild curve ormakes a lane change, resulting in production of a sense of wobble, suchas sideslip or lateral rocking about a roll axis. Such a sense of wobbleis a factor affecting the steering stability. There is a technique, forreducing the sense of wobble, in which tan 8 with respect to vibrationsin a low-frequency band is set in a predetermined range (PatentLiterature 1).

CITATION LIST Patent Literature

-   [Patent Literature 1] JP-A No. 2012-45104

SUMMARY OF INVENTION Technical Problem

However, there is a demand for further reduction of the sense of wobbleover the above-described known technique.

The present invention has been made to respond to the above demand andhas an object of providing a polyol composition and a flexiblepolyurethane foam from which a urethane pad capable of reducing a senseof wobble can be produced.

Solution to Problem and Advantageous Effects of Invention

To achieve the above object, a polyol composition for producing aflexible polyurethane foam set forth in claim 1 contains a polyolcomponent, an isocyanate component, and a polyrotaxane. Since thepolyrotaxane includes: an axle molecule including cyclic moleculesthereon in a skewered manner; and stopper groups placed at both ends ofthe axle molecule, the cyclic molecules of the polyrotaxane arecross-linked with a flexible polyurethane foam when the flexiblepolyurethane foam is formed by the reaction of the hydroxyl groups ofthe polyol component with the isocyanate groups of the isocyanatecomponent. In the polyrotaxane, the axle molecule slides through thecross-linking points (cyclic molecules) to such an equilibrium positionthat a tension acting on the flexible polyurethane foam becomesequalized, thus distributing the stress heterogeneity. Therefore, theflexible polyurethane foam can reduce the tensile stress as comparedwith a flexible polyurethane foam containing no polyrotaxane blended.

When lateral vibrations in a low-frequency band are input to a urethanepad made of this flexible polyurethane foam with a user sitting on theurethane pad, a vertical compressive stress due to the user's weight anda tensile stress due to the input of the lateral vibrations act on theurethane pad. The direction (inclination) of a resultant force obtainedby combining the compressive stress and the tensile stress can bebrought close to the vertical direction if the tensile stress of theflexible polyurethane foam can be reduced because the polyrotaxane hassubstantially no effect on the compressive properties of the flexiblepolyurethane foam. Thus, the angle of inclination of the user's hip(ischium) to the vertical direction due to the input of vibrations canbe reduced, which has the effect of reducing the sense of wobble of theurethane pad.

In a polyol composition set forth in claim 2, the hydroxyl value is 30to 85 mgKOH/g, which can prevent the cross-linking density of the cyclicmolecules from being too high. As a result, the degree of freedom atwhich the cyclic molecules can move along the axle molecule after beingcross-linked can be ensured. Thus, in addition to the effects of claim1, the effect is produced of ensuring the effect of reducing the tensilestress of the flexible polyurethane foam.

In a polyol composition set forth in claim 3, the polyrotaxane isblended in 0.9 to 30 parts by mass relative to 100 parts by mass of thepolyol component. Therefore, in addition to the effects of claim 1, theeffect is produced of preventing the polyrotaxane from interfering withthe foaming of the flexible polyurethane foam and surely reducing thetensile stress of the flexible polyurethane foam.

In a flexible polyurethane foam set forth in claim 4, the polyolcomposition according to claim 1 is foamed and cured, which has the sameeffects as claim 1.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic view of the microstructure of a flexiblepolyurethane foam according to one embodiment of the present invention.

FIG. 2 is a schematic view of the microstructure of the flexiblepolyurethane foam when a tension is applied thereto.

FIG. 3A is a schematic view showing a stress acting on a urethane padand FIG. 3B is a schematic view showing a stress acting on aconventional urethane pad.

FIG. 4 shows a force-deflection curve when test pieces of flexiblepolyurethane foams have been compressed.

FIG. 5 shows stress-strain curves when a tensile force has been appliedto test pieces of flexible polyurethane foams.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a description will be given of a preferred embodiment ofthe present invention with reference to the accompanying drawings. FIG.1 is a schematic view of the microstructure of a flexible polyurethanefoam 10 according to one embodiment of the present invention and FIG. 2is a schematic view of the microstructure of the flexible polyurethanefoam 10 when a tension is applied thereto. As shown in FIG. 1, theflexible polyurethane foam 10 includes: polymers 11, 12 obtained byreaction of hydroxyl groups of a polyol component with isocyanate groupsof an isocyanate component; and a polyrotaxane 13. The polyrotaxane 13has a structure in which an axle molecule 15 includes a large number ofcyclic molecules 14 to skewer them through their openings and stoppergroups 16 bind to both terminals of the axle molecule 15. The stoppergroups 16 prevent the cyclic molecules 14 from sliding off the axlemolecule 15. The flexible polyurethane foam 10 has a structure in whichthe polymers 11, 12 are cross-linked with the cyclic molecules 14 of thepolyrotaxane 13.

As shown in FIG. 2, the polyrotaxane 13 allows the cyclic molecules 14to be free to move along the axle molecule 15. When a tensile force isapplied to the flexible polyurethane foam 10, the cross-linking points(cyclic molecules 14) of the polyrotaxane 13 move (the pulley effect),so that local generation of stresses in the cross-linked structures canbe reduced. Thus, the tensile stress (tensile modulus) of the flexiblepolyurethane foam 10 can be reduced. In contrast, when a compressiveforce is applied to the flexible polyurethane foam 10, a compressivestress generates between the polymers 11, 12 and the polyrotaxane 13 hassubstantially no effect on the compressive properties of the flexiblepolyurethane foam 10.

With reference to FIG. 3, a description will be given of a sense ofwobble which a urethane pad 20 (urethane pad) as one of applications ofthe flexible polyurethane foam 10 gives a user H. FIG. 3A is a schematicview showing a stress acting on the urethane pad 20 and FIG. 3B is aschematic view showing a stress acting on a conventional urethane pad P.FIGS. 3A and 3B show a state where the user H sits on the urethane pads20, P. Note that the arrows U-D, L-R, and F-B show the verticaldirection, the right to left direction, and the front-to-rear direction,respectively, of vehicles (not shown) on which the urethane pads 20, Pare mounted.

As shown in FIGS. 3A and 3B, when the user H sits on each of theurethane pads 20, P, a compressive stress F1, F4 in the verticaldirection (direction of the arrow U-D) and a tensile stress F2, F5 inthe lateral direction (direction of the arrow L-R) act on each urethanepad 20, P by the user's weight. The tensile stress F2 of the urethanepad 20 is smaller than the tensile stress F5 of the urethane pad P sincethe polyrotaxane 13 (see FIG. 1) is blended in the urethane pad 20. Theinclination of the resultant force F3 obtained by combining thecompressive stress F1 and the tensile stress F2 with respect to thevertical direction can be smaller than the inclination of the resultantforce F6 obtained by combining the compressive stress F4 and the tensilestress F5 with respect to the vertical direction because the compressivestresses F1, F4 in the vertical direction acting on the respectiveurethane pads 20, P are approximately equal to each other.

When in this condition there is an input of vibrations in alow-frequency band (for example, about 1 Hz) in the lateral direction(the direction of the arrow L-R), as produced when a vehicle goes arounda mild curve or makes a lane change, the direction and magnitude of thetensile stress F2, F5 change and the direction and magnitude of theresultant force F3, F6 also change accordingly. The urethane pad 20 canbring the direction (inclination) of the resultant force F3 close to thevertical direction as compared with the direction of the resultant forceF6 of the urethane pad P. As a result, the urethane pad 20 can have asmall angle of inclination of the hip (ischium) of the user H to thevertical direction due to the input of vibrations as compared with theurethane pad P. Thus, the urethane pad 20 can reduce the sense of wobblethat the user H feels.

Referring back to FIG. 1, a description will be given of thepolyrotaxane 13 essential for the flexible polyurethane foam 10. Noparticular limitation is placed on the type of the cyclic molecules 14of the polyrotaxane 13 except that they are included on the axlemolecule 15. Examples that can be cited as the cyclic molecule 14include cyclodextrins, crown ethers, benzo-crowns, dibenzo-crowns,dicyclohexano-crowns, calixarenes, cyclophanes, cucurbiturils,porphyrins, lactams, and derivatives or modified forms of thesecompounds. The cyclic molecules 14 can be used in the form of a singlecompound of the above compounds or a combination of more than one ofthem. The cyclic molecule 14 is sufficient if it is substantially cyclicand even an incompletely closed ring, such as a C-shape, can be used asthe cyclic molecule 14. The incompletely closed cyclic molecule 14 mayhave a helical structure.

The cyclic molecule 14 used is a cyclic molecule having one or moretypes of functional groups among hydroxyl group, carboxyl group, aminogroup, epoxy group, isocyanate group, thiol group, aldehyde group, andso on. This is for the purpose of, when the polyol component reacts withthe isocyanate component, cross-linking them through the functionalgroup with the polyrotaxane 13. Although the functional group of thecyclic molecule 14 is not limited to these types, it is preferably agroup not reacting with the stopper groups 16.

The functional group of the cyclic molecule 14 may be bonded directly orthrough a spacer to another cyclic molecule 14. Although no limitationis placed on the type of the spacer, the spacer can be added to providehandleability, solubility, compatibility, and so on. Examples that canbe cited as the spacer include alkylene, polyethylene oxide,polypropylene oxide, polycaprolactone, and polyalkylene carbonate.

The functional group of the cyclic molecule 14 that can be suitably usedis a hydroxyl group or an isocyanate group. In the case of hydroxylgroup, while the polymers 11, 12 are obtained by the reaction of thehydroxyl groups of the polyol component with the isocyanate groups ofthe isocyanate component, it is possible to react and cross-link thehydroxyl groups of the cyclic molecules 14 with the isocyanate groups ofthe isocyanate component. In the case of isocyanate group, while thepolymers 11, 12 are likewise obtained, it is possible to react andcross-link the isocyanate groups of the cyclic molecules 14 with thehydroxyl groups of the polyol component. The particularly preferredfunctional group of the cyclic molecule 14 is a hydroxyl group. This isbecause the polyrotaxane 13 can be easy to handle.

It is preferred that their functional groups should be alkylated(modified) to adjust the hydroxyl value (functional value) because thecyclic molecules 14 control the reactivity. The hydroxyl value of thepolyrotaxane 13 is preferably set at 30 to 85 mgKOH/g and morepreferably set at 30 to 50 mgKOH/g. Note that the hydroxyl value ismeasured in conformity to JIS K1557-1:2007 edition (ISO 14900:2001edition).

Examples that can be cited as alkylation (modification) includeacetylation, propionylation, butyl esterification, ethyl carbamoylation,butyl carbamoylation, hexyl carbamoylation, octadecyl carbamoylation,and cyclohexyl carbamoylation, but are not limited to them.

If the hydroxyl value of the polyrotaxane 13 is 30 to 85 mgKOH/g, thiscan prevent the cross-linking density of the cyclic molecules 14 frombeing too high. As a result, the degree of freedom at which the cyclicmolecules 14 can move along the axle molecule 15 after beingcross-linked can be ensured, which can ensure the effect of reducing thetensile stress of the flexible polyurethane foam 10. In particular, ifthe hydroxyl value of the polyrotaxane 13 is 30 to 50 mgKOH/g, this canstably produce the effect of reducing the tensile stress of the flexiblepolyurethane foam 10.

Where the amount (maximum inclusion amount) at which the cyclicmolecules 14 can be maximally included on the axle molecule 15 is 1, theinclusion amount at which the cyclic molecules 14 are to be included onthe axle molecule 15 is preferably 0.1 to 0.6. If the ratio of theinclusion amount to the maximum inclusion amount of the cyclic molecules14 is 0.1 to 0.6, the degree of freedom at which the cyclic molecules 14can move along the axle molecule 15 can be ensured, which can ensure theeffect of reducing the tensile stress of the flexible polyurethane foam10. The ratio of the inclusion amount to the maximum inclusion amount ismore preferably 0.1 to 0.5 and still more preferably 0.2 to 0.4. This isfor the purpose of increasing the stability with which the pulley effectdevelops.

The axle molecule 15 is sufficient if it is a substantially linear chainmolecule, and it may have a branched chain so long as the cyclicmolecules 14 can be included thereon to cause the pulley effect.Examples that can be cited as the axle molecule 15 include: polyesters,such as polyalkylenes and polycaprolactones; polyethers, such aspolyethylene glycol; polyamides; polyacrylics, and benzenering-containing linear molecules. The axle molecule 15 preferably has amolecular weight of 1000 to 60000 and suitably has a molecular weight of5000 to 30000. Depending on the type of the cyclic molecules 14, smallermolecular weights of the axle molecule 15 show a tendency to lower thepulley effect and greater molecular weights of the axle molecule 15 showa tendency to lower the solubility and affect the foamability of theflexible polyurethane foam 10.

The axle molecule 15 preferably has functional groups at both terminals.This is for the purpose of reacting the functional groups with thestopper groups 16 to bond the stopper groups 16 to both the terminals ofthe axle molecule 15. The functional groups at both the terminals of theaxle molecule 15 can be appropriately selected depending on the type ofthe stopper groups 16 and examples thereof include hydroxyl group, aminogroup, carboxyl group, and thiol group.

The stopper groups 16 are atom groups placed at both the terminals ofthe axle molecule 15 and may be any atom groups so long as their sterichindrance (bulkiness or ionic interaction) enables the retention of astate where the cyclic molecules 14 are included on the axle molecule15. Examples that can be cited as the stopper group 16 include:dinitrophenyl groups, such as 2,4-dinitrophenyl group and3,5-dinitrophenyl group; cyclodextrins; adamantane groups; tritylgroups; fluoresceins; pyrenes; and derivatives or modified forms ofthem.

Next, a description will be given of a method for producing a flexiblepolyurethane foam 10. The description here is a method for producing aflexible polyurethane foam 10 in which a polyrotaxane 13 containinghydroxyl groups as functional groups of the cyclic molecules 14 is used.The flexible polyurethane foam 10 is produced in a manner that a mixtureliquid (polyol composition) containing a polyol component, an isocyanatecomponent, a medium containing a polyrotaxane 13 dissolved or dispersedtherein, a foaming agent, and a catalyst is poured into a molding tool(not shown) and then foamed and cured in the molding tool.

Examples that can be cited as the polyol component include polyols, suchas polyether polyols, polyester polyols, polycarbonate polyols,polyolefin polyols, and lactone-based polyols and a single polyol or amixture of two or more of these polyols can be used. Preferred amongthem are polyether polyols from the viewpoint of low cost of rawmaterials and excellent water resistance.

The polyol component may be used in combination with a polymer polyol asnecessary. An example that can be cited as the polymer polyol is oneobtained by graft copolymerization of a polyether polyol made ofpolyalkylene oxide with a polymer component, such as polyacrylonitrileor acrylonitrile-styrene copolymer.

The weight-average molecular weight of the polyol component ispreferably 3000 to 10000. If the weight-average molecular weight is lessthan 3000, the resultant foam will lose flexibility, which is likely tocause deteriorated physical properties and reduced elastic performance.If the weight-average molecular weight is more than 10000, the hardnessof the foam is likely to decrease.

Examples that can be used as the isocyanate component include variouskinds of known polyfunctional aliphatic, alicyclic, and aromaticisocyanates. Examples that can be cited include tolylene diisocyanate(TDI), diphenylmethane diisocyanate (MDI), dicyclohexylmethanediisocyanate, triphenyl diisocyanate, xylene diisocyanate, polymethylenepolyphenylene polyisocyanate, hexamethylene diisocyanate, isophoronediisocyanate, ortho-toluidine diisocyanate, naphthylene diisocyanate,xylylene diisocyanate, and lysine diisocyanate and these compounds maybe used alone or in combination of two or more.

Examples that can be cited as MDI-based isocyanate represented bydiphenylmethane diisocyanate include diphenylmethane diisocyanate (pureMDI), polyphenylene polymethylene polyisocyanate (polymeric MDI), theirpolymeric forms, their urethane-modified forms, their urea-modifiedforms, their allophanate-modified forms, their biuret-modified forms,their carbodiimide-modified forms, their uretonimine-modified forms,their uretdione-modified forms, their isocyanurate-modified forms, andmixtures of two or more of them.

Terminal isocyanate prepolymers can be used as the isocyanate component.Terminal isocyanate prepolymers are those obtained by previouslyreacting a polyol, such as a polyether polyol or a polyester polyol,with a polyisocyanate (such as a TDI-based isocyanate or an MDI-basedisocyanate). The use of such a terminal isocyanate prepolymer issuitable because this enables the control of the viscosity of themixture liquid (foaming stock solution), the primary structure of thepolymer, and the compatibility.

In this embodiment, MDI-based isocyanates are preferably used as theisocyanate component because they can be molded in elastic foams havingsmaller rebound resilience than elastic foams of TDI-based isocyanates.In the case where a mixture of an MDI-based isocyanate and a TDI-basedisocyanate is used, the mass ratio between MDI-based and TDI-basedisocyanates is 100:0 to 75:25 and preferably 100:0 to 80:20. As the massratio of the TDI-based isocyanate in the isocyanate component is largerthan 20/100, the sense of wobble of the resultant product (urethane pad)tends to decrease. When the mass ratio of the TDI-based isocyanate islarger than 25/100, the tendency is significant.

The isocyanate index of the isocyanate component (the percentage of theequivalence ratio of isocyanate groups to active hydrogen groups) is setat, for example, 85 to 130. The isocyanate index is determined relativeto all the active hydrogen groups in the other components, including thepolyol component, the polyrotaxane, the medium, and the cross-linkingagent.

The amount of the polyrotaxane blended is preferably 0.9 to 30 parts bymass relative to 100 parts by mass of the polyol component. This is forthe purpose of preventing the polyrotaxane from interfering with thefoaming of the flexible polyurethane foam and reducing the tensilestress of the flexible polyurethane foam. As the amount of polyrotaxaneblended relative to 100 parts by mass of polyol component is larger than30 parts by mass, the foaming of the flexible polyurethane foam tends tobe more inhibited. As the amount of polyrotaxane blended is smaller than0.9 parts by mass, the tensile stress of the flexible polyurethane foamtends to be less likely to decrease.

The medium is a compound serving as a solvent or a dispersion medium forthe polyrotaxane and good solvents having high solubility ofpolyrotaxane as well as poor solvents (dispersion media) having lowsolubility of polyrotaxane can be used as the medium without limitation.By dissolving or dispersing the polyrotaxane into the medium and mixingthe medium with the polyol component or the isocyanate component, it canbe prevented that the polyrotaxane is locally present in the mixtureliquid (polyol composition). As a result, the homogeneity of thepolyrotaxane in the flexible polyurethane foam can be increased.

Examples that can be cited as the medium include surfactants andhydroxyl compounds, such as alcohols. Examples of the surfactants thatcan be cited include anionic surfactants, cationic surfactants,non-ionic surfactants, and zwitterionic surfactants. These surfactantscan be used individually or as a mixture of two or more.

Examples of the anionic surfactants that can be cited includepolyoxyethylene alkyl ether acetates, dialkyl sulfosuccinates,dodecylbenzene sulfonates, laurylates, polyoxyethylene alkyl ethersulfates, alkyl allyl sulfonates, alkyl naphthalene sulfonates, alkylphosphates, alkyl sulfates, alkyl sulfonates, alkyl ether sulfates,alkyl sulfosuccinates, alkyl ester sulfates, alkyl benzene sulfonates,alkyl diphenyl ether disulfonates, alkyl aryl ether phosphates, alkylaryl ether sulfates, alkyl aryl ether ester sulfates, olefin sulfonates,alkane olefin sulfonates, polyoxyethylene alkyl ether phosphates,polyoxyethylene alkyl ether sulfates, ether carboxylates,sulfosuccinates, α-sulfo-fatty acid esters, fatty acid salts,condensates of higher fatty acids and amino acids, and naphthenates.

Examples of the cationic surfactants that can be cited includealkylamine salts, dialkylamine salts, aliphatic amine salts,benzalkonium salts, quaternary ammonium salts, alkylpyridinium salts,imidazolinium salts, sulfonium salts, and phosphonium salts.

Examples of the non-ionic surfactants that can be cited include: ethertype non-ionic surfactants, such as polyoxyethylene alkyl ether,polyoxyethylene lauryl ether, polyoxyalkylene alkyl ether,polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylenepolyoxypropylene monobutyl ether, polyoxyethylene alkylphenyl ether andpolyoxyethylene nonylphenyl ether; ester ether type non-ionicsurfactants, such as polyoxyethylene oleate ester, glycerin fatty acidester, polyoxyethylene stearate ester, polyoxyethylene fatty acid(lauryl) methyl ester, polyethylene glycol oleate monoester, andpolyoxyethylene sorbitan fatty acid ester; ester type non-ionicsurfactants, such as polyoxyethylene alkyl ester, sucrose fatty acidester, and sorbitan fatty acid ester; alkyl glycosides, such as octylglycoside; alkanolamide type non-ionic surfactants, such aspolyoxyethylene oleic amide and polyoxyethylene alkylamide; amineoxides, such as dodecyldimethylamine oxide and tetradecyldimethylamineoxide; alkylamine type non-ionic surfactants, such as polyoxyethylenealkylamine and polyoxypropylene polyoxyethylene alkylamine; and higheralcohols, such as cetanol, stearyl alcohol, and oleyl alcohol.

Examples of the zwitterionic surfactants that can be cited include:imidazoline derivatives, such as imidazolinium betaine;dimethylalkyllauryl betaine; alkylglycine; andalkyldi(aminoethyl)glycine.

Examples of the hydroxyl compounds that can be cited include: alcohols,such as polyols and aliphatic alcohols; phenols; and hydroxylgroup-containing compounds, such as hydrocracked products of polyols.When the medium is a polyol, the medium is part of the polyol component.The hydrocracked product of a polyol is obtained by reacting the polyolwith hydrogen to decompose hydroxyl groups and is a compound obtained bydecomposing the polyol to the extent that at least one hydroxyl group isleft.

It is preferred that the medium should contain as a main ingredient acompound having a weight-average molecular weight of 100 or more,preferably 300 to 2000, and more preferably 600 to 1000. If theweight-average molecular weight of the medium is 100 or more, thesolubility or dispersibility of the polyrotaxane into the medium can beensured. As a result, the homogeneity of the polyrotaxane in theflexible polyurethane foam can be increased. If the weight-averagemolecular weight of the medium is 300 to 2000, the effect of reducingthe tensile stress (tensile modulus) of the flexible polyurethane foamcan be ensured, depending on the amount of the medium or polyrotaxaneblended, while the solubility or dispersibility of the polyrotaxane intothe medium can be ensured.

Depending on the type of the medium, the amount of the medium blended ispreferably 50 to 200 parts by mass relative to 100 parts by mass ofpolyrotaxane. This is for the purpose of ensuring the solubility ordispersibility of the polyrotaxane into the medium and concurrentlypreventing that the amount of the medium blended is excessive relativeto the polyol composition (mixture) and thus the medium interferes withthe foaming of the flexible polyurethane foam. As the amount of themedium blended relative to 100 parts by mass of polyrotaxane is smallerthan 50 parts by mass, the solubility or dispersibility of polyrotaxaneinto the medium tends to decrease. As the amount of the medium blendedis larger than 200 parts by mass, the foamability of the flexiblepolyurethane foam tends to decrease.

The medium preferably contains as a main ingredient a compound havingone or two hydroxyl groups per molecule. This is for the purpose ofcross-linking the medium in the skeleton of the flexible polyurethanefoam and preventing, by means of the medium, the cross-linking densityof the polyrotaxane from becoming high. Since the cross-linking densityof the polyrotaxane can be prevented from becoming high, thus ensuringthe degree of freedom at which the axle molecule slides through thecross-linking points (cyclic molecules), the tensile stress of theflexible polyurethane foam can be surely reduced. Particularly with theuse of the medium having one hydroxyl group per molecule, the effect ofpreventing, by means of the medium, the cross-linking density of thepolyrotaxane from becoming high can be increased.

The medium is preferably a surfactant. The reason for this is that thedispersibility of the polyrotaxane into the medium can be increased.When the medium is a surfactant, the dispersibility of the polyrotaxanecan be improved and, thus, the homogeneity of the flexible polyurethanefoam can be further increased. The medium is particularly preferably ahydroxyl group-containing, non-ionic surfactant. The reason for this isthat it is possible to avoid having any effect on the reaction betweenthe polyol component and the isocyanate component because the non-ionicsurfactant includes no atom group that may be dissociated into ions.

The medium preferably contains a polyoxyalkylene group-containingcompound as a main ingredient. This is because the compatibility withthe polyol component forming a skeleton of the flexible polyurethanefoam can be improved. As a result, the dispersibility of thepolyrotaxane can be improved and, thus, the homogeneity of the flexiblepolyurethane foam can be further increased. Examples that can be citedas the polyoxyalkylene group-containing compound include polyoxyalkylenealkyl ether, polyoxyethylene polyoxypropylene alkyl ether,polyoxyethylene polyoxypropylene monobutyl ether, and polyoxypropylenepolyoxyethylene alkylamine.

Water is mainly used as the foaming agent. The molding may be performedusing the foaming agent, as necessary, in combination with a low-boilingorganic compound, such as a small amount of cylcopentane or normalpentane, isopentane or HFC-245fa, or by mixing and dissolving air,nitrogen gas, liquefied carbon dioxide or the like into the stocksolution with a gas loading apparatus. The preferred amount of foamingagent added is, depending on the set density of the resultant product,normally 0.5 to 15% by mass relative to the polyol component.

Various kinds of urethanization catalysts known in the art can be usedas the catalyst. Examples that can be cited include: reactive amines,such as triethylamine, tripropylamine, tributylamine,N-methylmorpholine, N-ethylmorpholine, dimethylbenzylamine,N,N,N′,N′-tetramethylhexamethylenediamine,N,N,N′,N′,N″-pentamethyldiethylenetriamine, andbis-(2-dimethylaminoethyl) ether; their organic acid salts; metalcarboxylates, such as potassium acetate and potassium octylate; andorganic metal compounds, such as stannous octoate, dibutyltin dilaurate,and zinc naphthenate. Also preferred are active hydrogengroup-containing amine catalysts, such as N,N-dimethylethanolamine andN,N-diethylethanolamine. The preferred amount of catalyst added is 0.01to 10% by mass relative to the polyol component.

As necessary, a polyvalent active hydrogen compound having a lowmolecular weight is used as the cross-linking agent. By means of thecross-linking agent, the elastic properties of the urethane pad can beeasy to control. Examples that can be cited as the cross-linking agentinclude polyalcohols, such as ethylene glycol, propylene glycol,1,4-butane diol, trimethylol propane, and glycerin; compounds obtainedby polymerizing ethylene oxide or propylene oxide with any of the abovepolyalcohols as an initiator; and alkanolamines, such asmonoethanolamine, diethanolamine, triethanolamine, andN-methyldiethanolamine. These compounds may be used individually or as amixture of two or more.

Furthermore, a foam stabilizer is used as necessary. Organicsilicon-based surfactants known in the art can be used as the foamstabilizer. The preferred amount of foam stabilizer added is 0.1 to 10%by mass relative to the polyol component. Moreover, as necessary, aflame retardant, a plasticizer, a cell opener, an antioxidant, anultraviolet ray absorber, a colorant, various fillers, an internal moldrelease agent, and/or other process aids are used.

Examples

The present invention will be described in further detail with referenceto examples; however, the present invention should not be limited tothese examples. The compounding ratios of mixture liquids (polyolcompositions) for molding urethane pads of Examples and ComparativeExamples are shown in Tables 1 and 2. The numerical values shown inTables 1 and 2 are represented in terms of unit mass (mass ratio). Eachisocyanate was blended so that the isocyanate index reached 100.

TABLE 1 Comparative Comparative Comparative Example 1 example 1 Example2 example 2 Example 3 Example 4 example 3 Example 5 Example 6 Example 7polyol 1 75 75 75 75 75 75 75 67 67 47 2 3 25 25 25 25 25 25 25 30 30 50medium 1 3 3 3 3 3 5 3 2 3 3 3 polyrotaxane 1 3 3 3 5 3 3 3 2 3cross-linking agent 0.75 0.75 1.00 1.00 1.00 1.00 1.00 2.00 2.00 2.00cell opener 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 2.00 foam 10.93 0.93 0.93 0.93 0.90 0.90 0.90 0.90 0.90 0.90 stabilizer 2 0.07 0.070.07 0.07 0.10 0.10 0.10 0.10 0.10 0.10 3 4 catalyst 1 0.35 0.35 0.350.35 0.35 0.35 0.35 0.30 0.35 0.40 2 0.10 0.10 0.10 0.10 0.10 0.10 0.100.10 0.10 water 2.90 2.90 2.90 2.90 2.90 2.90 2.90 2.90 2.90 2.20isocyanate 1 51.7 51.5 52.7 52.4 52.7 53.2 52.4 52.4 52.4 2 33.4 density(kg/m³) 62.5 62.2 62.0 63.0 63.0 62.6 62.0 62.0 61.0 60.9 25% ILD (N/314cm²) 289.7 289.0 294.6 290.6 287.5 267.6 295.7 283.3 259.6 295.3deflection (mm) 31.5 31.8 31.1 31.8 31.7 33.3 30.8 31.8 33.8 30.6tensile strength (kPa) 147.6 148.1 138.1 159.1 126.0 154.8 166.8 146.0129.5 159.3 elongation (%) 119.1 115.0 116.6 115.8 105.8 122.5 115.0102.5 99.2 97.5 tensile modulus (kPa) 82.6 87.0 77.6 89.1 78.9 85.5 96.081.5 74.2 83.3

TABLE 2 Comparative Example 8 Example 9 Example 10 Example 11 Example 12example 4 polyol 1 2 49 47 45 95 95 95 3 50 50 50 medium 1 2 1 3 5 5 5 5polyrotaxane 1 2 1 3 5 5 3 5 cross-linking agent 2.00 2.00 2.00 2.002.00 2.00 cell opener 2.00 2.00 2.00 2.00 2.00 2.00 foam 1 0.70 0.700.70 0.70 0.70 0.70 stabilizer 2 3 0.30 0.30 0.30 4 0.30 0.30 0.30catalyst 1 0.35 0.35 0.35 0.35 0.35 0.35 2 water 2.00 2.00 2.00 2.002.00 2.00 isocyanate 1 2 31.3 32.0 32.7 33.4 33.3 32.7 density (kg/m³)64.5 63.1 61.9 69.8 72.5 71.7 25% ILD (N/314 cm²) 298.9 246.0 198.9122.5 125.4 163.7 deflection (mm) 30.7 33.8 36.1 39.4 39.5 43.1 tensilestrength (kPa) 176.3 140.6 115.2 95.6 83.4 104.5 elongation (%) 90.096.7 98.7 108.3 109.1 103.3 tensile modulus (kPa) 93.6 67.8 54.7 50.449.0 60.2

The components shown in Tables 1 and 2 are as follows.

Polyol 1: polyether polyol EP828 (manufactured by Mitsui Chemicals,Inc.), 6000 weight-average molecular weight;

Polyol 2: polyether polyol EP330N (manufactured by Mitsui Chemicals,Inc.), 5000 weight-average molecular weight;

Polyol 3: polymer polyol POP3623 (manufactured by Mitsui Chemicals,Inc.);

Medium 1: non-ionic surfactant ET116B (manufactured by Dai-ichi KogyoSeiyaku Co., Ltd.), polyoxyalkylene alkyl ether (higher alcohol), 750weight-average molecular weight, one hydroxyl group per molecule;

Medium 2: polyether polyol EL720 (manufactured by Asahi Glass Co.,Ltd.), 700 weight-average molecular weight, two hydroxyl groups permolecule;

Polyrotaxane 1: an alkylated modified form of SH1310P (manufactured byAdvanced Softmaterials Inc.), in which SH1310P containing cyclodextrins(cyclic molecules) included on polyethylene glycol (an axle molecule) isalkylated at part of a hydroxyl group of the cyclic molecule with butylisocyanate, 11000 molecular weight of the axle molecule, 43 mgKOH/ghydroxyl value;

Polyrotaxane 2: SH1310P (manufactured by Advanced Softmaterials Inc.),11000 molecular weight of the axle molecule, 85 mgKOH/g hydroxyl value;

Polyrotaxane 3: SH2410P (manufactured by Advanced Softmaterials Inc.),in which cyclodextrins (cyclic molecules) are included on polyethyleneglycol (an axle molecule), 20000 molecular weight of the axle molecule,76 mgKOH/g hydroxyl value;

Cross-linking agent: diethanolamine;

Cell opener: EP505S (manufactured by Mitsui Chemicals, Inc.);

Foam stabilizer 1: L3625 (manufactured by Momentive PerformanceMaterials Inc.);

Foam stabilizer 2: SF2936F (manufactured by Dow Corning Toray Co.,Ltd.);

Foam stabilizer 3: SF2945F (manufactured by Dow Corning Toray Co.,Ltd.);

Foam stabilizer 4: B8736LF2 (manufactured by Evonik Japan Co., Ltd);

Catalyst 1: TEDA-L33 (manufactured by Tosoh Corporation);

Catalyst 2: Toyocat ET (manufactured by Tosoh Corporation);

Isocyanate 1: polymeric MDI, a mixture of 2,4′-MDI and 4,4′-MDI; and

Isocyanate 2: TM20 (manufactured by Mitsui Chemicals, Inc.).

These components were compounded in the mass ratios shown in Tables 1and 2. In Examples 1 to 12 (examples where a polyrotaxane was blended),a polyrotaxane was first added to a medium and the mixture was stirredat 50° C. for 30 minutes. After it was confirmed that the medium reacheda homogeneous solution, the solution was cooled to room temperature. Apolyol was uniformly mixed into the cooled solution and other componentswere then uniformly mixed to obtain a mixture liquid. Next, apredetermined amount of the mixture liquid was poured into an urethanepad molding tool (a lower portion thereof) having a predetermined shapeand foamed and cured in the cavity to obtain an urethane pad of each ofExamples 1 to 12. Since a polyrotaxane is dissolved or dispersed into amedium and other components are then mixed with the medium, thepolyrotaxane can be well dispersed in the urethane pad.

Each of urethane pads of Comparative Examples 1 to 4 (examples where nopolyrotaxane was blended) was obtained by compounding the individualcomponents in the mass ratio shown in Table 1 or 2 in the usual manner,uniformly mixing them, then pouring a predetermined amount of themixture into an urethane pad molding tool (a lower portion thereof)having a predetermined shape.

All the urethane pads were measured in terms of density, 25% ILD(hardness), deflection, tensile strength, elongation, tensile modulus.The results are shown in Tables 1 and 2. The density was calculated bytaking a cuboid test piece 100 mm long, 100 mm wide, and 50 mm high fromthe center of the urethane pad and measuring the mass of the test piece(unit: kg/m³).

The 25% ILD was measured after preliminary compression in the followingmethod conforming to the JIS K6400-2 (2012 edition) D method. Thepreliminary compression was performed according to the following manner.A test piece was taken from the urethane pad and put on a support platewith the center of the test piece aligned with the center of a pressingplate. For the test piece with a skin on one side, the test piece wasput on the support plate with its skin side facing the support plate.The position of the pressing plate (a 200 mm diameter flat disc) whenapplying a force of 5 N to the test piece thereby was considered to bean initial position and the thickness of the test piece at that time wasread to tenths of a millimeter. Thereafter, a pressure was applied tothe test piece by the pressing plate at a speed of 100 mm/min until 75%of the thickness of the test piece was reached and, then immediately,the pressing plate was moved back to the initial position at the samespeed (thus far is the preliminary compression). After the preliminarycompression, the test piece was allowed to stand for 20 seconds, pressedby the pressing plate to 25% of the thickness thereof at a speed of 100mm/min, and held for 20 seconds and the force at that time was read as ahardness (25% ILD, unit: N/314 cm²). JIS K6400-2 is a JapaneseIndustrial Standard established based on ISO 2439 (4th edition:published in 2008), ISO 3386-1 (2nd edition: published in 1986), and ISO3386-2 (2nd edition: published in 1997).

The deflection was measured after preliminary compression in thefollowing manner conforming to the JIS K6400-2 (2012 edition) E method.The preliminary compression was performed according to the followingmanner. A test piece was taken from the urethane pad and put on asupport plate with the center of the test piece aligned with the centerof a pressing plate. For the test piece with a skin on one side, thetest piece was put on the support plate with its skin side facing thesupport plate. The position of the pressing plate (a 200 mm diameterflat disc) when applying a force of 5 N to the test piece thereby wasconsidered to be an initial position and the thickness of the test pieceat that time was read to tenths of a millimeter. Thereafter, a pressurewas applied to the test piece at a speed of 50 mm/min until 75% of thethickness of the test piece was reached and, then immediately, thepressing plate was moved back to the initial position at the same speed(thus far is the preliminary compression). After the preliminarycompression, the test piece was allowed to stand for 60 seconds, apressure was then applied to the test piece at a speed of 50 mm/min bythe pressing plate until 75% of the thickness thereof was reached and,then immediately, the pressing plate was moved back to the initialposition at the same speed. During this operation, the deflection (unit:mm) when a load of 490 N was applied during application of the pressurewas measured.

The tensile strength was measured in the following manner conforming toJIS K6400-5 (2012 edition). A test piece was taken from the urethane padusing a dumbbell-shaped punching tool and two parallel marked lines wereput on a parallel portion of the test piece at equal distances from thecenter line of the test piece and perpendicularly to the longitudinaldirection so that the test piece does not deform. The distance betweenthe marked lines was 40 mm. Clamps of a tensile tester were fitted onthe test piece symmetrically so that a tensile force was uniformlyapplied to the cross section of the center of the test piece, thetensile test was conducted at a speed of 200 mm/min, and the maximumforce and the distance between the marked lines at breakage weremeasured. The tensile strength (unit: kPa) was determined by dividingthe maximum force at breakage by the cross-sectional area of the testpiece before the test. JIS K6400-5 is a Japanese Industrial Standardestablished based on ISO 1798 (4th edition: published in 2008) and ISO8067 (2nd edition: published in 2008).

The elongation at breakage (unit: %) was determined by dividing thedistance obtained by subtracting the distance between the marked linesbefore the test from the distance between the marked lines at breakageobtained by the above tensile test conforming to the JIS K6400-5 (2012edition) by the distance between the marked lines before the test.

The tensile modulus was measured in the following manner conforming tothe JIS K6400-5 (2012 edition). A test piece was taken from the urethanepad using a dumbbell-shaped punching tool and two parallel marked lineswere put on a parallel portion of the test piece at equal distances fromthe center line of the test piece and perpendicularly to thelongitudinal direction so that the test piece does not deform. Thedistance between the marked lines was 40 mm. Clamps of a tensile testerwere fitted on the test piece symmetrically so that a tensile force wasuniformly applied to the cross section of the center of the test piece,the tensile test was conducted at a speed of 200 mm/min, and the tensileforce and the distance between the marked lines were measured until thebreakage of the test piece.

A stress-strain curve was prepared by plotting the strain obtained bydividing the distance obtained by subtracting the distance between themarked lines before the test from the distance between the marked lineswhen a tensile force was applied by the distance between the markedlines before the test on the abscissa against the stress σ obtained bydividing the tensile force by the cross-sectional area of the test piecebefore the test on the ordinate. The tensile modulus is a value obtainedby dividing the tensile force when a predetermined elongation is appliedto the test piece by the cross-sectional area of the test piece beforethe test. In these examples, a stress (σ[Strain0.5]) at a strain of 0.5was determined and the value calculated from the calculation formulaσ[Strain0.5]/0.5 was defined as a tensile modulus (unit: kPa).

FIG. 4 is a force-deflection curve prepared based on measurement resultswhen test pieces of flexible polyurethane foams were compressed in themethod conforming to the JIS K6400-2 (2012 edition) E method. Theabscissa is deflection, the ordinate is force, and the solid line is aforce-deflection curve of Example 2. The force-deflection curve ofComparative Example 2 was superimposed on the force-deflection curve(solid line) of Example 2. FIG. 5 shows stress-strain curves preparedbased on measurement results when a tensile force was applied to testpieces of flexible polyurethane foams in the method conforming to JISK6400-5 (2012 edition). The abscissa is strain and the ordinate istensile stress. The solid line is a stress-strain curve of Example 2 andthe broken line is a stress-strain curve of Comparative Example 2.

Since as shown in FIG. 4 the force-deflection curve of Example 2 issuperimposed on the force-deflection curve of Comparative Example 2, itcan be said that the compressive properties of Example 2 areapproximately equal to the compressive properties of Comparative Example2. On the other hand, since as shown in FIG. 5 the inclination of thestress-strain curve (solid line) of Example 2 is smaller than theinclination of the stress-strain curve (broken line) of ComparativeExample 2, it has been confirmed that Example 2 can have a lower tensilemodulus than Comparative Example 2.

As shown in Table 1, Example 1 and Comparative Example 1 have the samecomposition, Example 2 and Comparative Example 2 have the samecomposition, and Examples 3 and 4 and Comparative Example 3 have thesame composition, each except for polyrotaxane. In comparison betweeneach pair and set above, it has been confirmed that each example isapproximately equal in density, 25% ILD (hardness), and deflection tothe relevant comparative example, but Examples 1 to 4 containingpolyrotaxane blended therein can have smaller tensile moduli thanComparative Examples 1 to 3 containing no polyrotaxane blended therein.

The amount of polyrotaxane blended in Example 4 is 5 parts by masslarger than the amounts (3 parts by mass) of polyrotaxane blended inExamples 1 to 3, but it has been confirmed that Example 4 can have asmaller tensile modulus than Comparative Example 3 containing nopolyrotaxane blended therein.

Examples 5 to 7 contain a polyol as a medium and are different in mediumtype from Examples 1 to 4. It has been confirmed that Examples 5 to 7whose media for dissolving polyrotaxanes are polyols can have smallertensile moduli than Comparative Examples 1 to 3 containing nopolyrotaxane blended therein.

As shown in Table 2, Examples 8 to 10 have the same composition exceptfor polyrotaxane and polyol 2 (polyether polyol). According to Examples8 to 10, it has been confirmed that as the amount of polyrotaxaneblended increases, the tensile modulus decreases.

Examples 11, 12 and Comparative Example 4 have the same compositionexcept for polyrotaxane. According to Examples 11, 12 and ComparativeExample 4, it has been confirmed that the tensile modulus can be reducedby the blending of a polyrotaxane.

Although description has been omitted in the above examples, it has beenconfirmed that when 0.9 to 30 parts by mass of polyrotaxane is blendedrelative to 100 parts by mass of polyol component by appropriatelyselecting the types and compounding ratios of the polyol component, theisocyanate component, the polyrotaxane, and so on, the tensile moduluscan be reduced as compared with the urethane pads containing nopolyrotaxane blended therein.

Although the present invention has been described so far with referenceto the embodiment, the present invention is not limited to the aboveembodiment and it can be easily inferred that various modifications andchanges can be made without departing from the spirit of the presentinvention. For example, the shapes described in the above embodiment aremerely illustrative and it is naturally possible to employ other shapes.

Although in the above embodiment the description has been given of theurethane pad (cushion material) made of flexible polyurethane foam to bemounted on a vehicle (motor vehicle), the present invention is notnecessarily limited to this. It is naturally possible to apply theflexible polyurethane foam to a cushion material or a back pad materialto be mounted on vehicles (for example, railway vehicles) other thanmotor vehicles, ships, boats, aircraft, or other conveyances or to acushion material or a mat material for furniture or the like.

Although in the above embodiment the description has been given of thecase where the polyrotaxane 13 is added into the polyol composition forproducing a flexible polyurethane foam 10, the present invention is notnecessarily limited to this and it is naturally possible to add across-linked polyrotaxane in which polyrotaxanes 13 are cross-linkedwith each other. The reason for this is that even if the polyrotaxane isa cross-linked polyrotaxane so long as the cyclic molecules 14 includesurplus functional groups, the cyclic molecules 14 can be cross-linkedwith a flexible polyurethane foam 10 when the flexible polyurethane foam10 is formed by the reaction of the hydroxyl groups of the polyolcomponent with the isocyanate groups of the isocyanate component.

Although in the above embodiment the description has been given of themethod for producing a flexible polyurethane foam 10 in which apolyrotaxane 13 containing hydroxyl groups as functional groups of thecyclic molecules 14 is used, the polyrotaxane 13 is not necessarilylimited to this. So long as the cyclic molecules 14 of a polyrotaxane 13include functional groups capable of cross-linking when the polyolcomponent reacts with the isocyanate component to form urethane, anysuch polyrotaxane 13 can be used without limitation.

Although in the above embodiment the description has been given of thecase where in producing a flexible polyurethane foam 10, a polyrotaxane13 is dissolved or dispersed in a medium before being mixed with apolyol component or an isocyanate component, the present invention isnot necessarily limited to this. With the use of a polyrotaxane (amodified form of polyrotaxane) having high affinity for the polyolcomponent or the isocyanate component, the polyrotaxane can be uniformlydissolved or dispersed in the polyol component or the isocyanatecomponent without using any medium.

1. A polyol composition for producing a flexible polyurethane foam, thepolyol composition containing a polyol component, an isocyanatecomponent, and a polyrotaxane, wherein the polyrotaxane includes an axlemolecule including cyclic molecules thereon in a skewered manner andstopper groups placed at both ends of the axle molecule.
 2. The polyolcomposition according to claim 1, wherein the polyrotaxane has ahydroxyl value of 30 to 85 mgKOH/g.
 3. The polyol composition accordingto claim 1, wherein the polyrotaxane is blended in 0.9 to 30 parts bymass relative to 100 parts by mass of the polyol component.
 4. Aflexible polyurethane foam obtained by foaming and curing the polyolcomposition according to claim 1.